Americans have been making a huge diet mistake for 100 years — here's what they should do instead

A little-known Los Angeles physician named Lulu Hunt
Peters played a major role in popularizing the use of calorie
counting for weight loss.

Her 1918 book, "Diet and Health With a Key to the
Calories," was the world's first best-selling diet
book.

Despite the ubiquity of calories today, recent studies
reveal that they are an imperfect measure of
nutrition.

In recent years, there's been a positive trend away
from focusing only on calories. Instead, experts are
encouraging people to eat more real food — vegetables, grains,
lean proteins, and healthy fats.

Standing before a room of women in Los Angeles, Lulu Hunt Peters
wrote a word on a blackboard that she said held the keys to
empowerment. It was a word most of her audience had never heard
before. Peters insisted it was just as important as terms like
"foot" and "yard," and that if they came to understand and use
it, they would be serving their country and themselves.

The word was "calorie." It was 1917, and although the calorie had
been used in chemistry circles for decades — and is often
credited to scientists such as Wilbur Olin Atwater and Nicolas
Clément — it was Peters who was responsible for popularizing the
idea that all we need to become healthier is knowing how much
energy is in our food and fervently cutting back the excess. But
her teachings weren’t all academic. She also referred to
overweight people as "fireless cookers" and accused them of
hoarding the valuable wartime commodity of fat "in their own
anatomy." Nevertheless, Peters' weight-loss program has become so
popular that some experts worry it now eclipses more important
aspects of nutrition.

Yet while Peters' concept of calories has managed to stick around
for 100 years, few have heard her name. As one of a handful of
female physicians in California at the turn of the 20th century,
Peters occupied a tenuous role as a health authority. After
initially opening up her own private practice, she struggled to
feel satisfied with her career. It was only after America entered
the first World War that Peters had the opportunity to find her
voice — first as a leader of a local women's club and finally as
America's most enduring diet guru.

'Hereafter, you are going to eat calories of food'

Lulu Peters was the picture of 1920s fashion. She wore her dark
hair in the flapper style, bobbed and adorned with glittering
headbands, and
sported luxurious furs. Her ears were decorated with gleaming
pearls. She wasn't rail thin, as the social mores of middle-class
white America said she ought to be, but she was 70 pounds leaner
than she had been when she'd graduated from medical school — a
point she emphasized with pride in a pamphlet she sold for 25
cents and later turned into the
world's first best-selling diet book.

Lulu Hunt Peters in
1923.Library of
Congress

When it came to the science of nutrition and weight loss, Peters
was in many ways decades ahead of her time. While ads in local
newspapers pushed women to try everything from smoking ("Reach
for a Lucky instead of a sweet!") to wearing medicated rubber
garments to lose weight, Peters was breaking down complex
scientific concepts like metabolism into accessible ideas that
could be used to slim down.

In 1910, when the average life expectancy was 49
years, most Americans had never heard of things like
calories, proteins, or carbohydrates. Even the
science of vitamins was a fledgling endeavor characterized by
a great deal of pseudoscience. Through her newspaper columns and
clubhouse talks, Peters introduced hundreds of people to these
ideas, and even began to link unhealthy eating with specific
diseases. She went so far as to recommend intermittent fasting
for those struggling to lose weight, a topic that is only now
beginning to emerge in the scientific literature.

Stanford
University

Still, it is what Peters taught her followers about calories that
has endured the longest, that all you need to do to lose weight
is consume fewer than you burn.

”Instead of saying one slice of bread, or a piece of pie, you
will say 100 Calories of bread, 350 Calories of pie," she wrote
in 1918. "Hereafter, you are going to eat calories of food."

'How dare you hoard fat when our nation needs it?'

In 1909, Peters was one of
about a thousand women across the country to graduate as a
doctor of medicine. War and its demand for medical workers had
helped temporarily ease some of the barriers blocking women from
entering universities, and in 1910 the percentage of women
physicians was
at an all-time high at 5%. Shortly after receiving her degree
from the University of California, Peters got a job
leading the Los Angeles County Hospital's pathology lab.
Several years later, even as the percentage of women medical
school graduates
receded to below 3%, she secured a role as the chair of the
public-health committee for the California women's club
federation of Los Angeles, a position that a local newspaper
described as having "more power than the entire city health
office."

Still, she occupied a tenuous position in a society led by men.
Even as a leading physician with two medical degrees, most of
Peters' roles were unpaid, including a one-year stint with the
American Red Cross in 1918 during World War I. Many of the
public-health events she attended were derided in local
newspapers as nothing more than "supper
parties" for "female physicians." And these roles, which were
already constrained by gender, were made even more exclusive by
the fact that they were volunteer-only. Women who didn't have
access to money — many of them women of color — were simply
barred from participating. Those who did attend made a show of
their wealth. With her high-society flapper fashion, Peters was
no exception.

Whatever signs of excess she displayed when it came to clothing,
however, Peters made up for in her approach to eating.

After having struggled with her weight for years early in her
career, Peters lost 70 pounds by carefully restricting the amount
of food she ate. Her diet was a seemingly logical extension of
basic chemistry: If you want to "reduce," you need to put less
energy into your body than it uses up. To do that, a unit of
measure she'd applied frequently as a student of child
nutrition at several Los Angeles hospitals, was key. She and
her peers had relied upon calculating the caloric content of baby
formula to ensure premature babies and other infants under their
care were properly nourished. Now, the measure seemed an easy way
to calculate the energy needs of adults.

As a leading member of the women's club federation, Peters became
a diet guru, frequently sharing bits of her dieting wisdom with
her fellow members. One day, shortly before leaving for her World
War I service with the Red Cross, she delivered a talk about
weight loss. In order for her audience to understand how she lost
weight, she had to introduce them to the unit of measure at the
foundation of her plan. The calorie, she explained, was a measure
of what she called "food values."

"You should know and also use the word calorie as frequently, or
more frequently, than you use the words foot, yard, quart,
gallon, and so forth, as measures of length and liquids," Peters
said.

American
National Red Cross volunteers at the Santa Fe hut in Los Angeles,
1918.Library of
Congress

Losing weight wasn't merely about meeting societal expectations,
though, at least in the way Peters chose to present it. Being
severely overweight was also linked with chronic illnesses such
as heart and kidney disease, she wrote. At the time, it was an
idea that was
just beginning to circulate among scientists. More important,
Peters offered calorie counting as a moral, patriotic duty.
Hungry troops at the front lines, Peters explained, needed the
calories that women like her could do without. What was fat, she
said, if not a high-energy resource that should be distributed to
the soldiers abroad?

"In war time it is a crime to hoard food, and fines and
imprisonment have followed the exposé of such practices," Peters
wrote. "Yet there are hundreds of thousands of individuals all
over America who are hoarding food, and that one of the most
precious of all foods! They have vast amounts of this valuable
commodity stored away in their own anatomy."

United States Food
Administration

Peters even went so far as to describe the discomfort of dieting
as a physical reminder of their American loyalty and an easier
way to deal with rationing. If the food they didn't eat didn't go
directly to the troops abroad, their leftovers could be used to
feed their children: "That for every pang of hunger we feel we
can have a double joy, that of knowing we are saving worse pangs
in ... little children, and that of knowing that for every pang
we feel we lose a pound."

It may have sounded like a noble goal at first, but Peters had
taken the idea of calorie counting too far.

An imperfect science

In a world dominated by celebrity fad diets that range from the
absurd, like Reese Witherspoon's alleged "baby-food diet," to the
absurdly unaffordable, such as Gwyneth Paltrow's $200 "moon
dust"-infused breakfast smoothie, calories can seem like the
most scientific option for improving your health. But there is
more guesswork involved in calorie calculations than you might
think.

The current system of calorie counting on which our nutrition
labels are based "provides only an estimate of the energy content
of foods," Malden C.
Nesheim, a professor of nutrition at Cornell University, said
at a
2013 meeting of the international nonprofit Institute for
Food Technologists.

Traditionally, scientists calculated the energy content of foods
using a large piece of machinery called a bomb calorimeter. The
process involved placing a sample of food into the device,
burning it, and measuring how much the water in a surrounding
container heated up. Since a Calorie raises the temperature of a
liter of water by 1 degree Celsius, the
calorie count would be found by calculating the change in the
water's temperature multiplied by the water's volume. Today, we
use a shortcut called the Atwater system, named after
agricultural chemist Wilbur Olin Atwater.

Atwater — who actually wanted to use his work in the 1890s to
help
poor people get the most calories for their money —
determined the average number of calories in four main energy
sources: carbs, fats, protein, and alcohol. Fats, he found, were
the most energy-dense, being worth about 9 calories per gram,
while proteins and carbs were roughly equal at about 4 calories
per gram. Alcohol was worth about 7 calories per gram.

The Atwater system is
how the calorie counts on nutrition labels have been
determined by the US Department of Agriculture since 1988.
Before that, they were done by hand. Using this method, you'd be
able to determine that a slice of wheat bread with 3 grams of
protein, 9 grams of carbs, and 1 gram of fat had roughly 60
calories.

Here's the problem: Not all of us process all foods the same way.

"It's definitely not just 'calories in and calories out' because
two people could be [burning] more and consuming less and one
person gains and one doesn't," says Cara Anselmo, a nutritionist
and outpatient dietitian at New York's Memorial Sloan-Kettering
Cancer Center. "There are metabolic differences person to
person."

These variations mean that each of us needs a different amount of
energy from our food, and it can vary substantially by the day.
One issue that the Atwater system will never account for, Anselmo
says, is the delicate balance of hormones that guide everything
from appetite to digestion. These hormones can be influenced a
great deal by our previous history of weight loss or weight gain.

"We find that with people who lose a significant amount of
weight, hormones play an important role too. So someone who's
always been at 150 pounds can actually get away with eating more
calories than someone who was at 250 pounds and lost 100 pounds.
Your body is producing fewer of the hormones that make you feel
full and more of the hormones that make you hungry," Anselmo
says.

This means that Peters, who lost a substantial amount of weight
before writing her best-selling diet book, might have had to
limit her diet more than someone who had always weighed what she
did.

In a large review
of studies published in the Journal of Nutrition, Purdue
University scientists found that whole tree nuts and peanuts have
roughly 15% fewer calories than the figure calculated using the
Atwater method. Although nuts are high in fat, the researchers
found, a significant portion of those oils end up being secreted
when we eat them. Another study published in the British Journal
of Nutrition in 2012 came to a similar conclusion about
pistachios, finding that they had about
5% fewer calories than originally assumed.

When calories aren't king

Let's say that at lunchtime you're given two options with the
exact same number of calories. You can either have a ham
sandwich, potato chips, and a can of soda or a salad and a
whole-grain roll. Which would you choose?

You might be tempted to pick the sandwich and soda. After all, if
they stack up the same in terms of calories, you might as well
pick the one you can taste, right?

According to Peters and the many popular modern diets she
influenced, the answer is yes. But it's not that simple. While
counting calories can be a useful tool in a bigger toolkit for
weight loss, it is not a perfect solution for healthy eating,
especially when it's used in isolation.

Nichola Whitehead, a
registered dietitian with a private practice in the UK,
summarizes the problem this way: "While calories are important
when it comes to losing, maintaining, or gaining weight, they are
not the sole thing we should be focusing on when it comes to
improving our health."

Take the following two daily meal plans, for example, both of
which are about 2,000 calories:

Business Insider/Samantha Lee

While they tally up to the same number of calories, the two plans
are far from equal.

"Both of these would give you the same number of calories, but
only one of them will leave you feeling satiated and satisfied
and give you the energy you need," says Whitehead.

That's because the meal on the right doesn't provide what
Whitehead calls "balance" — essentially the right mix of
proteins, complex carbohydrates, and fruits and vegetables that
your body needs
to be properly fueled in the long term. From the frosted
cereal at breakfast to the white-bread sandwich at lunch to the
refined pasta at dinner, the meal plan on the right is based
around refined carbohydrates, which the body breaks down quickly.
That means they'll give you a short burst of energy and make you
feel full for a few hours, but probably leave you hungry before
your next meal.

To keep energy levels up and keep you full and healthy for the
long term, your diet needs to feed more than your stomach. It has
to satiate your muscles, which crave protein, your digestive
system, which runs at its best with fiber, and your tissues and
bones, which work optimally when they're getting vitamins from
food.

How we got to now, from grapefruit diets to Weight Watchers

It wasn't until 1990 that calories made an appearance on the food
we buy, and they weren't
required by law until four years later.

Before that, there was simply no way to know for sure what was in
the food you bought. Several years after Peters gave her calorie
talk,
Spam debuted as one of the first processed convenience foods.
When World War II broke out, the easy-to-eat, no-spoil food was a
hit among soldiers, and for the next 20 years, conflict, rather
than craving, shaped the American palate. "In the universe of
processed food," Anastacia Marx de Salcedo writes in
"Combat-Ready Kitchen," "World War II was the Big Bang." The
1960s saw the invention of two more processed-food milestones:
The
first chicken nugget and high-fructose
corn syrup.

Perhaps in response to these unhealthy eating trends, severe diet
fads emerged for each decade from Peters' day to the present. In
the 1930s, about a decade after Polish biochemist Casimir Funk
first recommended people get enough of certain
micronutrients called "vitamines" (later found in abundance
in citrus fruits and veggies), the first grapefruit diet emerged,
followed by a banana-and-skim-milk diet promoted by United Fruit,
the planet's leading banana importer. Several decades later,
Weight Watchers
surged in popularity, and in the 1970s, women were encouraged to
take
sleeping pills whenever they felt hungry.

Throughout history, most of these diets were heavily marketed to
women, something that's still true today. Nevertheless, in
Peters' day, she claimed to see weight loss as a tool that she
and other women could use to liberate themselves, or, in her
words, to become more "efficient."

Today, neither the mantra of "calorie is king" nor the allure of
fad diets appears to have won out in the global battle for our
waistlines. In a hint that calories are here to stay, President
Obama in 2010 introduced a piece of legislation requiring every
large American restaurant chain to display
calorie counts on their menus. Just last summer, singer
Katy Perry claimed the "M Diet," otherwise known as eating
only raw mushrooms for one meal a day for two weeks, helped her
lose fat in select areas of her body. Nevertheless, there is a
move toward eating a more well-rounded diet based on vegetables,
whole grains, lean proteins, and healthy fats. It's a trend that
dietitians and public-health experts say they're encouraged by.